My Windhager experience

[Deering]

Hi All, last fall I installed a Windhager pellet boiler in my house up here in Alaska. Thought I'd do a quick recap of my experience.

The house: Built in 1979 with hot water baseboard and zone valves, it includes a mother-in-law apartment and heated workshop. All told, the heated area is around 4,500 sf. I've upgraded the insulation over the years. The climate here is fairly mild Maritime Pacific, think Seattle 10-15 degrees colder.

The heating system: The Biowin 150 was replacing a 120 kBtu oil boiler. A 15 kW boiler (51 kBtu) is a lot smaller than the system it was replacing so I was concerned about output. I knew that most times the oil boiler was oversized, but there were those infrequent cold spells when it worked pretty hard to keep up. I'd modeled the heat load with the Build It Solar calculator (http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm) and it indicated that a 60 kBtu boiler would be adequate. However, the boiler was also making my domestic hot water for the house and apartment. So my solution was to add in a 10 kW auxiliary electric 'peaking' boiler to handle any peak loads when the pellet boiler couldn't keep up.

Why a Windhager pellet boiler: I've been burning wood all of my life, but pellets were a new thing for me until a few years ago when I installed a couple Quadrafire pellet stoves in my house. I loved those things! Auto ignition, thermostat controlled, clean combustion, and low ash... But they had a few problems - I couldn't heat my apartment without installing a stove in the apartment and expecting the renter to deal with the stove. They wouldn't heat my domestic hot water. And they needed to be refueled every couple days. A boiler with bulk storage would solve all of that. I sold the Quadrafires in one day on Craigs List.

I saw Windhagers when I was at the Heating the Northeast with Biomass conference a couple years ago. Highly recommend that conference - if you're a wood energy nut you'll be a kid in a candy store. Lots of great technology on display there, much of it from Europe. I was attracted to the simplicity of the Windhager design, and the quality of the construction. The price points were very attractive as well. Windhager competes in the same market space in Europe as Okofen and Froling and others, and they're all excellent boilers - I wouldn't hesitate to install any of them.

The fuel: Here in Juneau we don't have access to natural gas, so most of our heating is with heating oil or some electric resistance. Current oil prices are a bit over $4 per gallon the last time I checked. Pellets aren't generally available in bulk and have to be shipped up from the Lower-48 - despite all of our trees here we only have two pellet mills in the state, with poor transportation access to them. I source my pellets from the local Home Depot - a bag goes for an astronomical $6.38 per bag ($319/ton), which includes a lot of embedded shipping cost. But that's equivalent to oil at about $2.65 per gallon, so the savings are substantial.

I built a plywood bin in my garage that holds about a ton of pellets. It has a hopper bottom with pneumatic pellet transfer pickups in the bottom. The pellets automatically transfer over to the boiler when its 'day hopper' gets low. I can back my pickup into the garage with a pallet load of pellets right next to the bin and fill the bin in about 20 minutes - less if my wife helps cut open bags. The bin lasts me about 6 weeks during the coldest part of the winter. Often when I swing past Home Depot I'll pick up a dozen bags just to keep the bin topped off. It's not been any hassle at all.

The installation: Because there was no local boiler supplier, I installed the boiler mostly myself. I don't generally recommend it. It was a lot of work and there are some specifics about the boilers that need to be commissioned by someone knowledgeable about these boilers. But I wanted to learn, and learn I did. Many, many kudos to Marc Caluwe, the U.S. distributor of these boilers, for all of his assistance and advice during the process.

The performance: There were two kinks that needed to be worked out of the initial system. The first kink was the integration with the electric boiler - I wanted the electric to only come on when the pellet couldn't keep up. A more sophisticated control system likely would have solved all of that, but I settled on a time delay relay system that slowed down the response of the electric boiler. Ultimately I found that the electric wasn't necessary - the pellet boiler was able to carry the entire load and the electric was placed in standby mode.

The other kink was that my distribution system consists of multiple relatively small zones of high temperature baseboard with on/off valves. This proved to be challenging to the Windhager because a zone would call for heat, the boiler would go through the ignition process, and before it was even totally up to temperature, the zone was satisfied and the boiler started shutting down. This short-cycling wasn't an efficient way to operate the boiler. My solution was to install a 85-gallon thermal storage buffer tank in the system. This tank separated the boiler from the zones, so all the boiler responded to was the temperature in the tank. This greatly slowed down the response time and allowed the boiler to fully modulate with long run times, and then long idle periods. This cost me about an extra $1,000 for the tank and pump system, but it was money very well spent - it made all the difference in the system.

Once the kinks were worked out, the boiler operated flawlessly. Absolutely flawlessly. Other than going down and petting it occasionally, I hardly know it's there. But I do show it off whenever possible. I've performed one scheduled cleaning of the boiler, and even with having to read the manual while I was doing it, it only took me about 45 minutes with a brush and vacuum. Nowhere near as nasty of a job as cleaning my old oil boiler.

Since 1 January 2014 I've tracked every pellet that has gone into this boiler and every electron it's consumed. I have an electric data logger on the system and I document every bag of pellets I pour into the bin. The results have been impressive:
- The system is far more efficient than my old oil boiler - I've calculated a 22% improvement in thermal efficiency over the previous system, which I attribute to a combination of a more efficient, modulating boiler, the thermal storage, and a better control scheme that leads to fewer standby losses.
- My dollar savings are 56% compared to the average oil usage of the previous three years if that oil had been at the current price of oil - this is due to a more efficient system and cheaper fuel (pellets). I'm saving nearly $1,500 per year.
- At local electric rates of about 11.4 cents per kWh, the entire system is costing about 22 cents per day of electricity to operate.

Bottom line: I'd install this boiler again in a heartbeat. It has exceeded my expectations. If you're burning oil now, don't wait years for your oil boiler to wear out. Convert to a high efficiency pellet boiler today - the payback may be sooner than you expected, especially if the price of oil spikes again in the future (and do you figure it won't?).

 

[maple1]

Sounds like a great experience - glad it worked out so good.

Big change in mindset here over the past 4 years or so - I no longer have an oil tank, and pellet (& electric) things are on my 'future considerations' list. Can't believe I stuck with oil for all those years even though it was blowing dollar bills up my chimney keeping our water hot. Ignorance is bliss I guess. I'm just hoping the pellet supply situation improves here a bit the next few years.

 

[velvetfoot]

I love it. Hope to be burning pellets in my 100/150 this winter. 4500 ft2! Your insulation must be great, cold maritime climate or not. I figure to be setting it at 100 (34,000 btu/hr).

 

[Deering]

I love it. Hope to be burning pellets in my 100/150 this winter. 4500 ft2! Your insulation must be great, cold maritime climate or not. I figure to be setting it at 100 (34,000 btu/hr).

To be more accurate, about 1,500 sf of that space is garage and shop that I keep in the 50's when I'm not actively working in it. The insulation in the place is pretty good, but not extraordinary. Only so much you can do with existing construction without getting into heroics.

The biggest challenge the system faces is first thing in the morning when it's trying to bring the house up to temperature while at the same time providing HW for showers. The thermal storage has made a huge difference in that regard. It has a large 'battery' of hot water available to it to instantly meet these load spikes.

 

[velvetfoot]

I think I'm going to be glad I didn't oversize it.

Your pellet storage scheme sounds great.

My oil boiler system has a 'priority' switch on it, which shuts out the other heating zones in favor of the indirect water heater. I too am getting a buffer tank, which also has a hot water coil in it. I'm still going to burn some wood, so the buffer tank should smooth things out when demand on the pellet boiler is low.

 

[velvetfoot]

Say Deering, you wouldn't be able to post any pictures, would you? I'd be real interested since I am starting the install.

 

[Deering]

Sure...now that I figured out how to post em. Here's the pellet bin in my garage. It has a hopper bottom. The vacuum tubes go out the back through the wall and to the boiler in the room behind it. Note that you can just see the top of the clipboard hanging on the wall to the top right - that's where I log every bag of pellets that goes into it.


Here's the boiler.


Here's the whole system. Note it's a bit amateur since I don't have access to pro pipe insulation and the like so I did the best I could...it works. And don't look too hard at my solder joints...but they don't leak! Still a few odds'n'ends to clean up from the old system.
Six zone valves on the back wall. The shiny tank is the 85-gallon thermal storage. The gray boxes to the left of the buffer tank are the zone controllers. To the left of them is the Kill-O-Watts electric data logger. Just to the right, immediately out of the frame (but you can see in the reflected tank) is the electric boiler.


Here's the Caleffi 281 Biomass circulator that transfers between the boiler and the buffer tank. The unit's designed to prevent water colder than 130F from returning to the boiler, which would cause condensation of corrosive flue gases. It incorporates a mixing valve with a wax 'spring' that controls the mixing of the supply and return water so that the return is always at 130F or above. As the boiler supply water gets hotter and/or the buffer tank warms up, less boiler water is mixed into the return until finally it's all coming from the buffer tank. It provides a lot of peace of mind that your boiler is being protected. Something like this is essential when you're using thermal storage - there are cheaper systems, but this just happens to be 'set & forget'. The black in the pic is the insulated foam clamshell that surrounds the unit.

 

[Mpodesta]

Sure...now that I figured out how to post em. Here's the pellet bin in my garage. It has a hopper bottom. The vacuum tubes go out the back through the wall and to the boiler in the room behind it. Note that you can just see the top of the clipboard hanging on the wall to the top right - that's where I log every bag of pellets that goes into it.

That Sir, is a badass setup! kudos on that!

 

[velvetfoot]

Very awesome. I hope to emulate you, but I ain't gonna top that shiny tank!!

I have a few questions. I don't mean to sound pushy or anything, but I'm right at the stage of buying stuff and making decisions.

Can I ask you about your stove pipe? It looks like 6" double wall, right? What make? How did you make the transition from the boiler to the pipe - some kind of 5 to 6" increaser? Brand? What kind of barometric damper are you using; is it working well for you? I looks like all the joints are siliconed-does the thing have to come apart to clean?

I like your temperature gauges. Do you remember who makes them? Are they surface mount or...?

Thanks.

 

[Deering]

Yeah, that shiny tank is certainly upstaging my pretty European boiler!

The black flue pipe is just single-walled stove pipe - 6". There's about 5 ft of it total before it connects to the double-walled class-A metal-bestos flue pipe in the ceiling that goes up through the roof. It's not an ideal arrangement. A perfect arrangement would have 5", double-walled flue pipe connecting to a 5" liner running down my existing flue, but none of that stuff is available up here in Alaska, so we make do. The goal is to keep the flue gases moving up and out before they have time to cool and condense. I had planned to crawl up on the roof last weekend to see how things were looking from above, but I got overcome by other projects. Maybe this evening. I'll provide a field report when I do. If I see considerable buildup, I'll think about paying the bucks to add a smaller liner...or just put it on a regular cleaning schedule.

At the boiler end, the boiler comes with an adapter that converts it from the metric standard to a 5". I then slipped a 6" to 5" reducer on it to get to the 6" black stove pipe that you see.

If you look carefully at the first boiler pic, you can just see the damper and a black 6" cap below it to the lower right behind the boiler. Per Marc Caluwe's recommendation, I installed the barometric damper downstream of the boiler, meaning that at the flue outlet of the boiler I installed a 6" tee, with one end heading up toward the chimney flue pipe (the stuff with the orange silicone) and the other heading down to the damper with a cleanout cap beyond it. This did two things: 1) In the event of any brief smoking during startup, none of the smoke would be likely to leak out of the damper into the boiler room; and 2) now I had a convenient cap that I could pull off to inspect and clean the lower end of the flue pipe. So far the flue at that end has been very clean, with only a small amount of fugitive ash collecting in the cap when I pull it off.

The barometric damper is a Field Controls 'Type RC'. It has worked perfectly since I installed it.

Temperature gauges - most of them are cheap surface mounted units that I purchased through Pex Supply. They read consistently 10-20F low, but that's OK for my purposes since I'm only looking to see if a given zone is hot or not. I have a couple gauges that are in-flow units and they appear to be far more accurate (and expensive and effort to install...).

 

[velvetfoot]

If things go well, I too am doing 6" stove pipe, only double wall DuraVent DVL. Does your 5" to 6" increaser go OVER the boiler flue outlet pipe? It appears the adapter I am getting will slip over it. Did you fasten it, ie, drill holes through the flue outlet pipe and screw it on?

I'm not sure why there would be less smoke coming out of the damper at that location, but the important thing is that it works.

I've been vacillating over what the best pipe arrangement would be. For the least flow restriction, I could use a 45 on each end with a baro damper installed in a tee on the lower part of the straight section. I figure cleaning the chimney is an annual event and I might want to take the entire stove pipe down for cleaning anyway. Or....I could put a cleanout tee at the bottom of the chimney where the stove pipe connects, and then put another tee under that for the barometric damper and which would also provide a cleanout for brushing the chimney from below. I still wouldn't have an easy way to clean the stove pipe like you do, however.

I guess I'll figure it out when the stuff comes, lol.

 

[maple1]

I don't have a pellet boiler, but I'll throw my 2 cents in on the stove pipe stuff.

My boiler has a T on the boiler outlet. One side of the T goes towards the chimney (sort of), at a slope closer to horizontal than vertical (never meaured it, but it's not uphill by a lot), for about 2' before the pipe makes another 90 to hit the chimney, going past my baro on the way, another 2' or so run. The other side of the T at the back of the boiler just has a cleanout cover on it. I have found that 90% of whatever ash makes it out of my boiler but does not make it all the way up the chimney settles in that first sloped run. I just have to pop that cleanout cover off, pull the ash out of the pipe into a bucket, pop it back on, and I'm good. Twice a year. I plan to never have to take my stove piping apart. I also use my baro as a second pipe access point, but it has turned out to only be used for inspection. I started out sticking a shop vac hose into it - but a couple weeks ago I checked out my entire piping & chimney setup and found practically nothing downstream of that first sloping pipe, since I last looked up my chimney back in February sometime. I haven't cleaned my chimney in 21 full months of burning - so I should never have to do that again either. I do also have a second cleanout cover at the very bottom of my chimney on another T - but when I took that off a couple weeks ago, there was only a half inch or so of ash in it. That was kind of long winded, but my main point was - if you put a T where you might otherwise put an elbow, with a cleanout cap on the 'other end', chances are you will never have to take your pipe apart.

(With the usual 'I'm no Pro' disclaimer).

I would imagine the Windhager would make even less mess - it is indeed a fine looking piece of gear.

 

[velvetfoot]

I do also have a second cleanout cover at the very bottom of my chimney on another T

That's where I'm thinking of adding another T with the baro damper, in my second scenario. I think it would be nice to get away with no 90s, but you have two 90s with good performance-very short run though, it seems-mine is a little longer.
I'm probably looking for something like this, but it's not available in the system I chose:
(broken image removed)